A desirable goal in the design and fabrication of IR radiation detectors is an extension of the detector spectral sensitivity to wavelengths longer than approximately 3 microns.
One type of IR detector which accomplishes this upper wavelength extension is known as a superconducting heterodyne mixer. This type of detector can be fabricated to exhibit an upper cut off wavelength of approximately 100 microns, which is within a range of wavelengths considered as Very Long Wavelength IR (VLWIR) radiation. However, this type of detector is known to be wavelength selective and to absorb only a single spectral line at such longer wavelengths. Furthermore, for use at longer wavelengths this type of detector is not readily adaptable to fabrication with a fine geometry required to produce a relatively large and compact array of detectors.
It is therefore one object of the invention to provide a radiation detector which absorbs a significantly broad range of wavelengths of VLWIR.
It is another object of the invention to extend the spectral sensitivity of nonequilibrium superconducting detectors.
It is another object of the invention to provide a superconducting radiation detector having an improved surface morphology which facilitates the fabrication of multilayer Superconducting-Insulating-Superconducting (SIS) and Superconducting-Insulating-Normal (SIN) type junctions.
It is one further object of the invention to extend the spectral sensitivity of nonequilibrium High Temperature Superconducting (HTS) detectors by providing a proximity layer on a surface of the HTS material, the proximity layer exhibiting a smaller, induced, energy gap than the adjacent HTS material and a correspondingly longer cutoff wavelength.